1. Field of the Invention
This invention relates generally to grain harvesting and processing and, more specifically, to methods and apparatus for grain harvesting and simultaneous measurement of grain properties. In particular, this invention relates to grain harvesting systems utilizing multiple test weight buckets and multiple sensors, including ultrasonic and radar level sensing devices.
2. Description of the Related Art
Various grain characteristic information is used in seed research to determine which varieties or hybrids to advance to commercialization. During harvesting, such information may include parameters such as grain moisture content and grain bulk density (or "test weight"). For example, the yield of a number of different seed grain varieties or hybrids may be evaluated by growing them under differing conditions in individual "test plots". These individual plots may be harvested and analyzed for data, such as test weight and moisture content. To increase the efficiency of grain variety evaluation test plots, usually about 20 feet long and containing 2 rows of plants spaced about 30 inches apart, are typically planted adjacent each other so that a number of test plots may be harvested and analyzed using a single combine and associated measuring equipment. These test plots are typically planted sequentially with a vacant area of about 2-3 feet separating successive plots.
In the past, combines have been modified to include a "weigh bucket" to selectively receive and weigh grain harvested from each individual test plot. Weigh buckets typically include instrumentation that measures the plot weight, grain moisture and test weight in conjunction with a mechanical apparatus that holds a known volume of grain. In a typical test plot harvesting operation, a combine harvests the grain from a single plot and stops or delays prior to moving to the next plot so that the grain may be analyzed before being transferred to the combine's grain tank. During this time, the grain is threshed, cleaned, and deposited into a weigh bucket where weight and moisture content is typically measured. Once analysis of the grain has been completed, grain is discharged from the weigh bucket and the combine continues to the next test plot where grain is again collected and the process repeated. One disadvantage of past methods for harvesting and analyzing test plots is the time lost waiting for weigh bucket instrumentation to stabilize so that grain analysis may be completed and grain from one test plot discharged from the weigh bucket before moving to the next test plot.
Another disadvantage of previous test plot harvesting methods is that previous methods have typically employed segmented weigh bucket devices having separate containers for measuring test weight and grain weight, respectively. These methods utilize a "test weight device" for measuring grain density that is a relatively small container of known volume separate from the larger weigh bucket container where grain weight is measured. Such test weight devices have typically used mechanical "leveling" devices to remove excess grain from the top of the test weight device, so that test weight may be calculated from the known volume and measured weight of grain within the test weight device before the grain is dumped from the test weight device. Mechanical leveling devices have typically included a leveling arm attached to a motor, linear actuator, solenoid, or hydraulic or pneumatic cylinder which mechanically sweeps across the top of the device to remove excess grain. The use of two containers complicates harvesting and measuring operations, potentially increasing the delay in harvest time between adjacent plots. In addition, the separate test weight device and its associated components include a number of mechanical parts, such as levers and motors, linear actuators, solenoids, or hydraulic or pneumatic cylinders which complicate the overall system. Finally, measurement and calculation of test weight from a small sub-sample of the test plot harvest, coupled with reliance on mechanical action of a leveling arm to produce a known volume of grain may result in decreased test weight accuracy. Accuracy may be further compromised by the vibration of a moving harvesting machine during measurement and calculation.
Another segmented grain measuring device employs separate chambers for receiving and measuring grain. In this device, grain is received in an entrance chamber and transferred to a volume sizing chamber of known volume, where grain moisture is measured. A level detector is employed to initiate closing of a first gate between the entrance chamber and the volume sizing chamber when it senses that grain has completely filled the volume sizing chamber, thereby sizing a fixed volume grain sub-sample to be weighed. A second gate between the volume sizing chamber and a weigh chamber is then opened to transfer grain to the weigh chamber where the grain sub-sample is weighed. A third gate is then opened to discharge the grain. This segmented device also has the disadvantage of complicated mechanical operation.
In an effort to increase the efficiency of test plot harvesting and analysis, two-plot combine designs have been developed. In a two-plot combine device, two separate and parallel test plots may be harvested and analyzed simultaneously by a single combine having an individual weigh bucket for each test plot. Although such two-plot designs increase the efficiency of harvesting and analysis by allowing two test plots to be simultaneously processed, it is still typically necessary for a combine to delay between harvesting sequential sets of test plots.